The three primary approaches used to clean commercial and residential carpets are steam or hot water, foam and dry systems. Dry-type carpet cleaning systems are further divided into two broad categories, namely, those using a dry or substantially dry powder and those using granules which are slightly moistened with cleaning solvents for dirt removal. The inventive machine has utility for both categories of dry systems but relates primarily to those using granules rather than powder. Such machine also has utility in situations where only carpet vacuuming is performed. That is, its aggressive, long-bristled brushes are highly effective in removing loose sand and other soil not requiring the application of solvent-bearing material.
Of the dry granular carpet cleaning systems, the best known and most widely used is the HOST.RTM. dry extraction system offered by Racine Industries, Inc. of Racine, Wis. The HOST.RTM. system applies granules to carpet fibers using a machine as shown in Rench et al. U.S Pat. Nos. 2,842,788 and 2,961,673. Such machine, sold under the HOST.RTM. trademark, is devoid of vacuum capability and has a pair of spaced brushes which counter-rotate at relatively low speed (about 350 rpm) to stroke the cleaning granules into, through and across carpet fibers. The granules are referred to as "dry" and are substantially so although moistened with cleaning solvents. When stroked as described, these granules "scrub" soil and dirt from such fibers including oily and non-oily soil. The carpet is cleaned by working the HOST.RTM. machine across it in different directions. During the cleaning process, granules migrate to the carpet backing adjacent the base of the fiber. Granules also adhere lightly to the fibers along their lengths. Following cleaning, conventional carpet vacuum machines are used for removing the dirt-ladened granules.
Conventional vacuum machines are not ideally suited for the removal of such dirt-ladened granules although such machines do a reasonably acceptable job of such removal. In particular, most such machines employ a single "beater bar" which rotates at high speed and which uses spaced rows of relatively short bristles. A few such machines have two counter-revolving beater bars which are constructed and operate in much the same way. Such high speed beater bars with short bristles are more effective in removing granules near the tops of the fibers but significantly less so as to granules which are "deep down" in the carpet.
Another disadvantage with many such conventional carpet vacuuming machines is that a shroud surrounds at least a portion of the periphery of the beater bars and such shroud is very closely spaced to the bars or may lightly contact the bar bristles. Redistribution of granules during carpet cleaning is an important function since such granules should be repeatedly brushed through the carpet fibers. The absence of a significant space between the bristles and the shrouds of many conventional machines prevents dry carpet granules from being cast about by the brushes during the cleaning operation
Yet another disadvantage of such machines is that the beater bar(s) are often driven by smooth-surfaced, flexible rubber belts which wrap partially around the bar. The solvent used to moisten the cleaning granules often causes the belt to slip, thereby temporarily disabling the bar(s).
Still another disadvantage is that vacuum nozzles on most such machines face directly or angularly downward toward the carpet and operate simultaneously with the beater bars. Therefore, it is not possible to first brush the granules into the carpet and then later remove them by independently-operable vacuum nozzles
Further, the embodiment of carpet brushing and carpet vacuuming capabilities in two separate machines means that both such machines must be available to complete the cleaning process. This represents an extra equipment expense and for the professional carpet cleaner, it also represents added time (reflected in employee wages) required to get the necessary machines to the job site and to later remove such machines Examples of conventional vacuum machines are shown in U.S. Pat. Nos. 1,891,504 and 4,426,751.
In addition to the foregoing, several other patents show machines which combine brush and vacuum features for removing dirt from a surface. Nordeen U.S. Pat. No. 4,426,751 and Smellie U.S. Pat. No. 1,891,504 show carpet cleaning machines having two counter-revolving beater bars with brushes thereon. Shrouds are in very close proximity to the tips of the brushes and extend around a portion of the bar perimeters. In the nozzle shown in the Nordeen patent, at least a portion of the shroud must contact the beater bar bristles in that the shrouds are said to strip away material which clings to the periphery of the brushes Vacuum inlets are positioned forward and aft of the bars and carpet brushing and vacuuming occur simultaneously.
The machine shown in Swiss Patent No. 96633 has a single revolving brush and a shroud spaced from the brush and extending more than halfway around its periphery. The machine has two vacuum nozzles, the inlets for which face downward toward the surface to be cleaned and are spaced above such surface
Wolter et al. U.S. Pat. No. 3,540,072 shows a floor scrubbing machine having two machine-supporting, counter-revolving brushes, the rotational axes of which are normal to the floor. Two bar-like, downward-facing suction nozzles are mounted one each crosswise at the front and rear of the machine. These nozzles can be raised during scrubbing operations and lowered for drying the wet floor. The suction air stream can also be disabled during scrubbing.
Waldhauser U.S. Pat. No. 4,817,233 shows a floor scrubber having downward-facing, squeegee-type vacuum nozzles, one each positioned forward and aft of a single brush. The vacuum passages are defined in part by a shroud positioned in close proximity to the brush. One of the two nozzles is always closed by an inwardly-turned flexible nozzle lip. The particular nozzle which is closed is a function of the direction of machine travel.
Warner U.S. Pat. No. 1,211,902 shows a railway track cleaner uses a revolving drum with outwardly extending blades to clean the track. A U-shaped shroud has a pressurized air inlet and a vacuum nozzle whereby cleaning air may be introduced into and removed from the shroud.
A type of system used for cleaning carpets with powder is the DRYTECH cleaning machine sold by Sears, Roebuck & Company. The machine has a self-contained vacuum capability and one beater bar with several rows of short-bristled brushes. Such bar is within a shroud which generally conforms to the shape of the bar and by which vacuum is selectively applied. As the brush alone is rotated at high speed, powder is dispensed through two slits, one on either side of the bar between the bar and the shroud. Later, the vacuum is actuated and dry powder (with dirt entrained) is dislodged by the brush and drawn away by vacuum.
Another type of machine used to apply dry cleaning powder to carpet fiber is made by Clarke-Gravely Corp. of Muskegon, Mich. and sold as the CLARKE CAPTURE carpet cleaning system. Such machine distributes cleaning powder onto the carpet and works the powder into and through the carpet fibers using a round, disk-like scrubber brush, the axis of rotation of which is normal to the carpet surface The machine vacuum system operates to reduce dust. After cleaning, a separate conventional vacuum machine is used to remove the powder.
None of the machines discussed above provide the advantages of a dual machine capability to first apply dry carpet cleaning granules using long-bristled, relatively stiff counter-revolving brushes, permit such granules to be freely redistributed along passages and through granule exit openings and then remove the dirt-ladened granules from the carpet by vacuuming. Earlier workers in this field have failed to understand how to make and deploy independently-operable vacuum nozzles to obstruct the openings and passages for granule removal subsequent to carpet cleaning. A machine having such capabilities would be an important advance in the art.